Method of and apparatus for coating strands



May 18, 1937.

C. M. UNDERWOOD METHOD OF AND APPARATUS FOR COATING STRANDS Filed June 1, 1933 EEEYQQE Y// ////////L//////// WVENTOA GM U/VDERWOOD Arm/min Patented May 18, 1 937 PATENT omor I METHOD OF AND APPARATUS FOR COAT- TRANDS ING S Carl M. Underwood, on Park, m, assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application June 1,.1933, Serial No. 673,857

11' Claims.

This invention relates to methods of and apparatus for coating strands.

Objects of the invention are to provide uniform and effective coatings for strands and effective and efficient methods of and apparatus for applying coatings to strands. f

In accordance with one embodiment of the invention, a steam wipe coating apparatus is provided having a steam outlet chamber provided with means for maintaining the chamber at an elevated temperature and provided with a down draft exhaust, and adapted to apply high melting point alloys or metals, such as zinc, to strands. The apparatus is also adapted to apply lead alloys which are incapable of being applied by mechanical wiping means.

I A complete understanding of the invention may be had by reference to the following description taken in conjunction with the accompanying drawing, in which Fig. 1 is a side elevation, partly in section, of an apparatus embodying the invention and by means of which the methodof the invention may be practiced and the strands of the invention made; and

Figure 2 is a fragmentary sectional view of the steam wiping head and steam outlet chamber.

In the drawing, which illustrates a preferred form of the invention, reference numeral 10 designates a reel upon which is wound a supply of strand material, such as wire II, to be coated.

From reel ill the strand material passes over pulley I 2 to a fluxing bath l3, which is designed,

.or tin-lead alloys which may contain bismuth or cadmium. Tin and lead form alloys in practically all percentages and these alloys may be applied to strands by this method and apparatus herein disclosed. The coating material is contained in a tank I! which may be heated by any suitable means. However, if a metal of high melting point is to be applied to the strand, the container I1 is preferably placed in a second container [8 having a lead bath therein. In order to heat the lead bath the container I8 15 provided with a plurality of tubular heating ele ments l9 containing electrical: heating elements for heating the bath. In this manner a uniform temperature is applied to the container I! so that excess of coating material applied thereto, next 2 passes to the wiping mechanism 23, where the excess coating material is removed as described in detail hereinafter, and then passes to a cooling device 24. The cooling device has an inclined groove through which the strand passes. and a stream of water is supplied to the groove from a pipe 25 having its outlet near the upper'end of the groove. The strand is thereby brought into contact with the cool water and chilled, after which it may be dried by means of a blast of air from a pipe 26 and passed over a pulley 2'! and a capstan 28 to a driven take-up reel 29.

The wiping mechanism 23 comprises a gas separating chamber 3| provided with a downwardly extending column 32 which passes through the molten lead bath in container l8 and is heated thereby. The wiping mechanism is mounted closely adjacent the edge of the container ll of the liquid coating material and comprises a die 33 of the wire drawing type but of substantially greater diameter than the strand H, thus allowing a substantial clearance be tween the'strand and die so that when the strand passes through the die in the bath l6, only, the

gross excess of coating material is removed by the die. The die, which may be of diamond or other hard material, is mounted on a pivotally supported bracket 34 by means of which the die may be swung upwardly and away from the bath H5 in threading the wire through the die at the beginning of the coating operation, since the heat of the bath I 6 is so intense as to make it inconvenient to thread the die in operative position. During operation, the bracket 3 is preferably secured in position by means oi. a thumb screw 35.

Mounted in alignment with the preliminary wiping die 33 is a steam wipe mechanism comprising a. block 36 having a conical chamber 31 therein, which opensinto a tube 38 having a conical interior wall 39. The chamber 31' is prov ded with an inlet for superheated steam ll.

2 y The block 36 is provided with an aperture through which a cone-shaped member 42 is inserted into the chamber. This member is provided withan internalbore of such size that it will not contact with the coated wire and the member is provided with a peripheral flange 43 for setting the member in the block 36. The distance the conical portion of member 42 ex-'- tends into chamber 31 may be varied by placing washers 44 under the flange 43. The wiping mechanism just described is designed to use superheated steam or other gas which entersthe chamber 31 through the inlet and passes through the narrow opening at the apex of chamber 31, thereby tending to produce a suction through the bore of member 42 and draw air from the exterior of the wiping mechanism. Such an infiux of air is undesirable since it prematurely chills the coating material and causes it to congeal on the strand and may be prevented by adjusting the membe'r42 by means of the washers 44 until'adjustment is reached, at which there is no influx of air at a given gas pressure. From the apex of the chamber 31, the velocity of the steam increases due to its expansion in tube 38 so that the strand is subjected to a wiping action by the movement of steam at a high velocity longitudinally of the wire for a substantial distance. The excess coating material remaining on the surface of the strand after its passage through die 33 is thereby removed and broken up into droplets which are separated from thesteam by gravity in chamber 3i and dropped intoa container 45 at the lower end of column 32. Preferably two containers 4! are provided in the base of the column so that when one container. is removed, the removed coatin material will drop in the other container. The steam'passes downwardly from the separating chamber 3| and is drawn laterally from the column 32 by an exhaust outlet tube 48. By thus providing a down draft exhaust, the droplets of coating material attain a suflicient downward momentum before reaching the exhaust outlet that they will continue downwardly into the containers 45, thereby preventing the accumulation of coating material in the exhaust outlet.

When zinc or other metals having a high melting point are used, it is necessary to prevent the coating material from freezing on the strand before being wiped. For, this reason the die 33 is mounted as nearly adjacent the bath of coating material as possible and the walls of the gas chamber 3| are heatedby providing a plurality of electrical'resistance elements 21 therein. The exterior of thischamberis also preferably provided with insulating material 48. The superheated steam, therefore, loses heat chiefly by the work performed from wiping the coating material, and the coating-material removed from the strandwill not tend to "collect on the back of the die or the walls of the inner walls of the chamber. Since the column 32 is immersed in the lead heating bath in container l8, this column will also be maintained at such a high temperature that the molten material will not adhere to the walls thereof. I

The thicknessof a coating remaining on the strand will be controlled by varying-the speed of the 'wire or the pressure of the gas, or both.

As an illustration of the steam temperature and pressure. used for steam wiping tin-lead alloy comprising 35% tin and 65% lead, the superheated steam may be introduced into the chamber 31 at a temperature of 750 F. and a gauge presis well known in the art. j

let connected to said'column,

alloy is 520 F and the steam in its expansion in moving through the tube 38 coolsdown to a temperature'of 250 F. In general the temperature of the superheated steam should be substantially higher than the melting point of the coating metal; otherwise the steam in expanding will cool to such a low temperature as to chill the coating metalland prevent eflective wiping of the coating.

The melting point of zinc alloys can be made substantially lower than ing the zinc with suitable metals; for instance, by alloying 95% zinc with 5% aluminum, the melting pointislowered from 187 F. to 116 F. Other suitable alloys which may be used are:'

ing a melting point of 700 F.; zinc 1'Z%" and cadmium 83% having a melting point of 506 1".;

andzinc 8% and tin 92% having a melting point of 376 F. These lower melting points result in the possibility of lowertemperatures for the superheated steam, which, aspointed out above. should be substantially higher than the melting point oi the coating alloy.

In some cases it may be desirable to apply a zincor zinc alloy coatinglto'tempered high carbon steel'wire. This may be done by running the wire at such a high speed that only the outer layer of skin of the "wire is heater appreciably. The coating may then be chilled, immediately upon leaving the'wiping head without destroying the temper of the wire. In galvanizing a-steel wire, of course, the wiremust first be fluxed as The expressions stra ",or' "strand material", as used in the specification and claimasre intended to embrace any elongated. material. such as strips, sheets, rods, or the like.

Whatisclaimed is: p

1. In an apparatus forcoating'strands, means for applying coating material to the strand, means for applying a heated'stream of gas to the strand to remove excess material therefrom, a gas chamber surrounding said means, down draft gas exhaust means said chamber. I v

2. In an apparatus for coating strands, means for applying coating material to the strand, means for applying a heated streamof gas to the strand to remove excess material therefrom, a

that of zinc by alloy-.

25% and lead 75%v havand a associated with gas chamber surrounding said means and having a gas chamber surrounding said means and having a downwardly extending column, means for heating said chamber, means for heating said column, an exhaust outlet connecte'dto said col-f umn, and means for collecting material removed from the strand in thebase of said column.

4. In an apparatus for coating a strand. means for applying coating material to the "strand,

meansfor applying a heated stream of gas to the strand to remove excess material therefrom, a

gas chamber surrounding said means and having I a downwardly extending column, an exhaust outmeans for collecting material removed from the strand in the base of said column, and heat insulating means over the exterior of said chamber.

5. In an apparatus for coating a strand, means for applying coating material to the strand, a gaschamber, means extending into said chamber for applying a heated stream oi. gas, to the strand, a die preceding said means for removing a portion of said material before said stream of gas is applied, and means for movably supporting the die on' a hinged arm provided with a locating latch to permit threading the strand therethrough.

6. A method of coating a strand which comprises moving the strand through a bath of molten coating metal and passing a stream of superheated steam longitudinally of the strand to remove the excess coating metal, the temperature of said superheated steam when it first strikes the strand being'higher than the melting point of the coating metal. a

7. The method of wiping a freshly applied molten metal coating on a moving body of small heat storage capacity which comprises simultaneous impingement of the body coating on opposite sides of the body by a aseous wiping medium having a temperature higher than the melting point of the metal coating directed with force thereupon to even and smooth the coating while arresting solidification thereof, the force of said wiping medium being sufficient to displace a portion of said metal coating.

8. The method of wiping-a freshly applied molten metal coating on a moving strand which comprises simultaneous impingement of the coating on opposite sides of the strand by a gaseous wiping medium having a temperature ing directed with force thereupon to even and smooth the coating while arresting solidification thereof.

9. The method .of wiping a freshly applied molten metal coating on a metal strand which comprises the steps of projecting a gaseous wiping medium having a temperature higher than the melting point of the metal coating on the strand with sufficient force to remove a portion of said molten coating and smooth the remaining ature than the melting point of the coating metal longitudinally, of the article to smooth the coating thereon.

11. In an apparatus for coating strands, means for applying a coating of molten metal to the strand, means for applying a heated stream of gas to the strand to remove excess coating metal therefrom, a gas chamber surrounding said means, a passage extending downwardly from' said chamber and having a normally closed bottom and an exhaust passage extending laterally from a position between the bottom of the passage and the chamber.

CARL M. UNDERWOOD.

higher than the melting point of the metal coat- 

